In recent years, mobile communication devices having built in cameras have become popular with consumers. Consumers can use cameras incorporated into their mobile communication devices to capture images, send and receive digital images, and/or participate in video conferences. Until recently, the demand for mobile communication devices with built-in cameras has not been very high because the built-in camera makes the mobile communication device prohibitively expensive. However, as technology improves and costs decrease, the demand for built-in cameras will continue to grow.
To meet the growing demand for built-in cameras, product manufacturers will need to find ways to improve camera modules for mobile communication devices. Currently, most camera modules for mobile communication devices have a fixed aperture controlling the amount of light that reaches the light sensor. Exposure control and compensation for varying light conditions is performed in software. In contrast, most digital cameras have a variable aperture that allows the consumer to select a desired aperture size, which is often referred to as an F stop.
While it would be desirable to have a variable aperture for a camera module in a mobile communication device, space limitations have hindered the widespread adoption and use of variable apertures. In conventional cameras, a mechanical iris is used to provide a variable size aperture for exposure control. A mechanical iris typically comprises a series of overlapping leaves attached to a surrounding ring. The ring may be turned manually or by a motor. As the ring is turned, the iris leaves expand or contract to vary the size of the aperture. In general, the space requirement for a mechanical iris is too large for most mobile applications where space is a precious commodity. Therefore, there is a need for an alternative to a conventional mechanical iris that is better suited for mobile applications.